Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,
Tel (Office): (865) 574-6124 (FAX): (865) 574-1268
The studies of radioactive decays often define the borders of known nuclei. In recent years we have witnessed several important experiments using decay spectroscopy methods that have helped us to understand better the structure and processes involving atomic nuclei. I would like to discuss two of them, both aimed at extremely rare phenomena: the discovery and properties of two-proton radioactivity (2p) and the identification of new superheavy elements (SHE).
In both cases, experimental progress was enabled by innovative methods.
The application of an Optical Time Projection Chamber allowed us to establish the correlations between two protons emitted in the decay of 45Fe produced in the fragmentation of a relativistic 58Ni beam (NSCL, Lansing, MI). The measured angular and energy distributions revealed the mechanism of 2p-radioactivity – strongly correlated emission of two individual protons. Two new experiments on the radioactive decay of 48Ni and 54Zn will be performed within next two to three years at the NSCL. The Z=26 45Fe and Z=30 54Zn nuclei can be interpreted as 2-proton holes and 2-proton particles around doubly magic Z=28 48Ni, respectively. These new studies will help us to establish nuclear structure related effects involved in the mechanism of 2p-radioactivity.
Studies at the Dubna Gas Filled Recoil Separator (JINR, Dubna, Russia) using radioactive actinide target materials from ORNL and an intense Z=20 48Ca beam have led to the discovery of new superheavy elements with atomic numbers Z=114 to Z=118. Experiments to extend the periodic table of elements to Z=119 and Z=120 atoms are planned in several laboratories. These projects count on using ORNL-produced Z=97 Bk and Z=98 Cf targets and Z=22 50Ti beam. The identification of new, very short lived activities requires an upgrade of present detection methods.
I will present the ideas for upgrading the SHE detection system and its commissioning at the HRIBF Recoil Mass Separator.